inspect before you connectsm - fia

Inspect Before You Connectsm

An Introduction to Fibre Optic Inspection & CleaningPaul Avison, JDSU

© 2011 JDS Uniphase Corporation | JDSU CONFIDENTIAL AND PROPRIETARY INFORMATION 2

“JDSU – who?”

Annual Revenue

Business Segments

Employees

Locations

Country Representation

Index Membership

$1.37B (FY10)

Leader in 3 key segments

≈ 4,900

Over 80 Sales and R&D sites globally

164 Countries

S&P 500


Business Segments

Solutions: Optical Communications, Commercial Lasers, and Photovoltaics.Applications: Network Equipment, Industrial and Consumer Products.

Communications and Commercial Optical Products (CCOP)

Solutions: Lab/Field Test and Service AssuranceApplications: Test, Monitoring and Analysis for Network Equipment and Networks (Telecom, Cable, Wireless, Datacom)

Communications Test and Measurement (CommTest)

Solutions: Custom Color, Custom Optics, and Authentication SolutionsApplications: Currency, Defense, Industrial and Consumer Products

Advanced Optical Technologies (AOT)


In a recent study by NTT-Advanced Technology, 98% of installers (blue) and 80% of network owners (red) reported that issues with connector contamination was the greatest cause of network failure.

Causes of Network Failure



� Inspection Overview

� Fiber Optic Connectors

� Contamination

� Simple Solution

� Case Studies

� Standards Update

� Pluggable Optics –How to Inspect?


Inspection Overview – Microscopes

DIRECT-VIEW SCOPE BENCH SCOPE

DIGITAL PROBEPROBE SCOPE & DISPLAYS

Part I: Fiber Optic ConnectorsUnderstanding Fiber Optic Connectors


Fiber Connectors Are Everywhere

Fiber optic connectors are common throughout the network, and they give you the power to add, drop, move and change the network.

Buildings

Multi-home UnitsResidential

CO/Head End

Local Convergence Point

Network Access Points

Feeder Cables

Distribution Cables

Drop Cables


Fiber Optic Connector

SC Connector

� The BODY houses the ferrule that secures the fiber in place.

� The FERRULE is a small cylinder where the fiber is mounted and acts as the fiber alignment mechanism. The end of the fiber is located at the end of the ferrule.

� The FIBER is comprised of 2 layers, the CLADDING and the CORE.

– The CLADDING is a glass layer surrounding the core, which prevents the signal in the core from escaping.

– The CORE is the critical center layer of the fiber and the conduit that light passes through.

BODYBODY

FERRULEFERRULE

FIBERFIBER

CLADDINGCLADDING

CORECORE

Fiber connectors have extremely tight tolerances with the potential to make a low loss connection. To achieve this potential, they must be handled and mated properly.


Anatomy of Fiber Connector

Light is transmitted and retained in the “CORE” of the optical fiber by total internal reflection.

Singlemode Fiber StructureSinglemode fibers carry a single ray of light, making them better in retaining the fidelity of light over long distances.

There are 3 major ZONESon the end face that are used to define the level of impact contamination may have on signal performance. Particles closer to Zone A (Core) will have more impact than those farther out.

CORECORE

CLADDINGCLADDING

FERRULEFERRULE

Fiber End Face View

ZONE A

ZONE B

ZONE C


Simplex vs. Multi-fiber Connectors

SIMPLEX CONNECTOR RIBBON CONNECTOR

� White ceramic or metallic ferrule

� One fiber per connector

� Common types include SC, LC, FC, E2000 and ST

� Multiple fibers in linear array (8, 12, 24, 48, 72, etc.) in single connector providing high-density connectivity

� Includes MPO or MTP®


Focused On the Connection

Fiber connectors are widely known as the WEAKEST AND MOST

PROBLEMATIC points in the fiber network.

Bulkhead Adapter

Fiber Connector

Alignment Sleeve

Alignment Sleeve

Physical Contact

FiberFerrule


Inspection Diagnosis – Connector Type

� Connector body type (SC, LC, ST, FC, MTP, etc.)?

� Polish (UPC or APC)?

� Patchcord or bulkhead?

Determining Connector Type

SC LC FC ST MPO/MTP

SC APC LC APC FC APC E2000 Transceiver


Inspection Diagnosis – Accessibility

Inspection Tips for Every Application

Physical Location

Optical Optical DevicesDevices

Printed Circuit Board Angled Mounting

� Is the port near a wall?

� What is the mounting configuration?

– Top of rack?

– Bottom of rack

– In a tight space?

Densely Populated

Specialty tips (e.g., Long Reach, 60-Degree Angled, etc.)

enable inspection when accessibility is limited.


What Makes a GOOD Fiber Connection?

� Perfect Core Alignment

� Physical Contact

� Pristine Connector Interface

The 3 basic principles that are critical to achieving an efficient fiber

optic connection are “The 3 P’s”:

Core

Cladding

CLEAN

Light Transmitted

Today’s connector design and production techniques have eliminated most of the challenges to achieving Core Alignment and Physical Contact.

Part II: Contamination

Understanding Contamination on Fiber Optic Connectors and Its Effect on Signal Performance


What Makes a BAD Fiber Connection?

� A single particle mated into the core of a fiber can cause significant back reflection, insertion loss and even equipment damage.

� Pressure is 40k PSI –45k PSI will cut steel

Today’s connector design and production techniques have eliminated

most of the challenges to achieving CORE ALIGNMENT and PHYSICAL

CONTACT.

What remains challenging is maintaining a PRISTINE END FACE. As a result,

CONTAMINATION is the #1 source of troubleshooting in optical networks.

DIRT

Core

Cladding

Back Reflection Insertion LossLight


Illustration of Particle Migration

� Each time the connectors are mated, particles around the core are displaced, causing them to migrate and spread across the fiber surface.

� Particles larger than 5µm usually explode and multiply upon mating.

� Large particles can create barriers (“air gaps”) that prevent physical contact.

� Particles less than 5µm tend to embed into the fiber surface, creating pits and chips.

11.8µ

15.1µ

10.3µ

Actual fiber end face images of particle migration

Core

Cladding


Contamination and Signal Performance

Fiber Contamination and Its Effect on Signal PerformanceCLEAN CONNECTION

Back Reflection = -67.5 dBTotal Loss = 0.250 dB

11

DIRTY CONNECTION

Back Reflection = -32.5 dBTotal Loss = 4.87 dB

33

Clean Connection vs. Dirty Connection

This OTDR trace illustrates a significant decrease in signal performance when dirty connectors are mated.


Original OTDR Trace


OTDR Trace after cleaning connector at event 2


Dirt Damages Fiber!

� Once embedded debris is removed, pits and chips remain in the fiber.

� These pits can also prevent transmission of light, causing back reflection, insertion loss and damage to other network components.

Most connectors are not inspected until the problem is detected… AFTERpermanent damage has already occurred.

Mating dirty connectors embeds the debris into the fiber.

Core

Cladding

Back Reflection Insertion LossLight

DIRTPITS(permanent damage)


Contamination Categories

� LOOSEMost contamination comes from dry particles that have fallen onto the end-face or have been “placed” there when handling.

� BONDEDMost stubborn particles are held in place with grease, oils or dried residue from a wet cleaning process.

� MATEDParticles on the end-face of a connector can also become embedded into the glass if mated with another connector.

CONTAMINATION MUST BE CLEANED from the end-face prior to mating in order to optimize the efficiency of an optical signal or interconnect.


Types of Contamination

A fiber end face should be free of any contamination or defects, as shown below:

Common types of contamination and defects include the following:

Dirt Oil Pits & Chips Scratches

SINGLEMODE FIBER


Where is it? – Proliferation of Dirt

There are a number of different sources where dirt and other particles

can contaminate the fiber.

� Test Equipment

� Dust Caps

� Bulkheads

� People

� Environment

Connectors and ports on test equipment are mated frequently and are highly likely to become contaminated. Once contaminated, this equipment will often cross-contaminate the network connectors and ports being tested.

Inspecting and cleaning test ports and leads before testing network connectors prevents cross-contamination.

Part III: Simple SolutionInspect Before You Connect



Follow this simple “INSPECT BEFORE YOU CONNECT” process to ensure

fiber end faces are clean prior to mating connectors.


• This workflow chart comes from AT&T Document ATT-TP-76461 titled “AT&T Fiber Optic Connector and Adapter Inspection and Cleaning Standards” - in the public domain.

• AT&T’s procedures call for continual inspection and cleaning.

• AT&T procedures starts with dry cleaning connectors for the first three cleanings.

Procedure Example – AT&T


Inspect and Clean Both Connectors in Pairs!

Inspecting BOTH sides of the connection is the ONLY WAY to ensure

that it will be free of contamination and defects.

Patch cords are easy to access and view compared to the fiber inside the bulkhead, which is frequently overlooked. The bulkhead side may only be half of the connection, but it is far more likely to be dirty and problematic.

Bulkhead (“Female”) InspectionPatch Cord (“Male”) Inspection


Proactive vs. Reactive Inspection

PROACTIVE INSPECTION:

Visually inspecting fiber connectors at every stage of handling BEFORE mating them.

Connectors are much easier to clean prior to mating, before embedding debris into the fiber.

REACTIVE INSPECTION:

Visually inspecting fiber connectors AFTER a problem is discovered, typically during troubleshooting.

By this time, connectors and other equipment may have suffered permanent damage.

Dirty Fiber PRIOR to MatingFiber AFTER Mating and

Numerous Cleanings

Dirty Fiber PRIOR to

Mating

Fiber AFTER Cleaning


Connector #1 - Clean


Connector #1 – Loose Contamination


Connector #2 - Clean


Connector #2 – After One Connection


Connector #2 – After Repeated Cleaning


Connector #1 – After One Connection


Connector #1 – After Repeated Cleaning

Part IV: Case Studies


Understanding Dynamic Range Issues in FTTx Networks – GPON

OLT

IO

ONT

IO

IO1:32

1

32

Splitter

F.O.

ONT

Case Study:


� Loss Budget ~28dB (Class B+ Optics)

� 1x64 splitter ~21dB (e.g. Fitel 1x64 PLC splitter)

� 15km of fibre ~4.5dB (best case)

� Budget for connectors/splices ~2.5dB

There is NO margin in a GPON network for bad connectors. One dirty connector, depending on the location, will take up to 64 customers out of service, and necessitate extra testing and a truck roll to clean or likely replace the connector.

G-PON Network Loss Budget


Data Centre – 40 or 100GBASE-SR10

From the IEEE802.3ba Standard

• Channel Insertion Loss 1.5dB, includes 150m of OM4 fibre (3.5dB/km at 850nm)

• Two MPO connectors – 8 or 20 fibres

• No margin for dirty connectors

Part V: Standards Update


Standards and Zones

� ZONES are used to prioritize evaluation criteria.

Zone A: Core Zone

Zone B: Cladding Zone

Zone C: Adhesive Zone

Zone D: Contact Zone

� Different failure criteria for defects and scratches are specified for each zone:

• Quantity and Size

• Location relative to core

Zone A

Zone D

Zone B

IEC 61300-3-35 – “Fibre Optic Connector Endface Visual and Automated

Inspection” has recently been published as an interoperability standard for

connector manufacturers and users.


Recommended Acceptance Criteria for SM-UPC Connectors (IEC 61300-3-35)

Zone Name(diameter) Scratches Defects

A, Core Zone

(0-25μm)none none

B, Cladding Zone

(25-120μm)none > 3μm width

no limit < 2μm

5 from 2 - 5μm

none > 5μm

C, Adhesive Zone

(120-130μm)no limit no limit

D, Contact Zone

(130-250μm)no limit none > 10μm


Recommended Acceptance Criteria for SM-APC Connectors (IEC 61300-3-35)


A, Core Zone

(0-25μm)< 4 scratches none

B, Cladding Zone


no limit < 2μm

5 from 2 - 5μm

none > 5μm

C, Adhesive Zone


D, Contact Zone



Recommended Acceptance Criteria for MM-PC Connectors (IEC 61300-3-35 Draft)


A, Core Zone


4 � 5μm

none > 5μm

B, Cladding Zone


no limit < 2μm

5 from 2 - 5μm

none > 5μm

C, Adhesive Zone


D, Contact Zone



Recommended Acceptance Criteria for SM-UPC Ribbon Fiber Connectors (IEC 61300-3-35)


A, Core Zone

(0-25μm)none none

B, Cladding Zone


no limit < 2μm

5 from 2 - 5μm

none > 5μm

Criteria must be applied to all fibres in the array for functionality of any fibres in

the array


Recommended Acceptance Criteria for MM-PC Ribbon Fiber Connectors (IEC 61300-3-35)

Zone Name(diameter)

Scratches Defects

A, Core Zone


4 � 5μm

none > 5μm

B, Cladding Zone


no limit < 2μm

5 from 2 - 5μm

none > 5μm

Criteria must be applied to all fibres in the array for functionality of any fibres in

the array


Part VI: Pluggable Optics

How to Inspect??


Example of TOSA & ROSA Structures

Special Lens

Ball Lens

Stub

TOSA ROSA-1 ROSA-2

Structure of TOSA with stub is similar to fiber connector.

Optical Sub Assembly

Example of Optical Data Link(SFF type)

Test vehicle for iNEMI study


Fiber Stub Devices


Non-Contact Lens Devices


Non-Contact Lens Inspection


Optical Transceivers / Receptacles


Contact Lens Inspection


Summary

� Connectors are valuable and essential, but they must be handled properly.

� CONTAMINATION is the #1 source of troubleshooting in optical networks.

� This challenge is easily overcome with proactive inspection and cleaning.

� Visual inspection of fiber optic connectors with a microscope is the only way to determine if connectors are clean before they are mated.

� Pluggable optical devices (XFP/SFP etc.) present significant issues in inspection and cleaning, and correct understanding of the various interfaces is vital for success in network installation and troubleshooting.

� Proactive inspection is easy, and the benefits are:

– Reduced Network Downtime

– Reduced Troubleshooting

– Optimized Signal Performance

– Prevention of Network Damage

� Always “INSPECT BEFORE YOU CONNECT”

inspect before you connectsm - fia

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